Arrangement for drawing sand and sand mixtures from a container



Feb., 27, 1951 H. TUTscH ARRANODNENT FOR DRAWING sAND AND SAND MIXTORESFROM A CONTAINER 2 Sheets-Sheet 1 Filed sept. 29, 1945 Fig. 1

H5 n im ww. M A S l Hy Feb. 27, T1951 H, TUTSCH 2,543,344

ARRANGEMENT FOR DRAWING SAND AND SAND MIXTURES FROM A CONTAINER FiledSept. 29, 1945 2 Sheets-Sheet 2 Arran/KVS Patented Feb.. 27, 1951ARRANGEMEN'I FOR DRAWING SAND AND SAND MIXTURES FROM A CONTAINER HenryTtsch, Zurich, Switzerland, assignor to Aktiengesellschaft',

Zollikon-Zurich,

Switzerland, a. Swiss corporationl Application September 29, 1945,Serial No. 619,301 In Switzerland October 3, 1944 1I) Claims.

The present inventionY relates toan arrangement for drawing sand andsand mixtures indry condition from a container for the'y purpose offeeding them to a spray pistol. In sand-blasting apparatus, arenaceousquartz of regular granulation is drawn from a container and blown bymeans of compressedair to thespray pistol. The devicesin use withsand-blasting apparatus cannot be used for drawingv oil sand, and sandmixtures, as sand of irregular granulation or sand mixtures form lumps.Moreover, in sand-blasting an irregular passage of materia-lis ofr noimportance. With sand mixtures, however, which are moistened duringspraying with some liquid e. g. water, in order to be sprayedv on inpasteform, an absolutely'regularv passage of materialv is essentialforthe consistency of the paste. In order to achieve this, it isnecessary that the amount of sand conveyed should be exactly regulatedby some mechanical meansV before actual spraying.

The aim of the present invention is to create an arrangement by means ofwhich sand and sand mixtures of the most varied granulation can be drawnfrom a container without interruption and in aA constant flow'.

According to the invention, the sand orl sand mixture is drawn bymeansof a screw conveyor from an open container without interruption and in aconstant ow and is conveyed to within reach of an air-now which carriesit along to a spray pistol.

The arrangement which carries out the process consists in anon-revolving conveyor tube dipping into a rotating container which canbe iilled from above. In this tube a screw conveyor turns and raises thematerial in the conveyor tube. The latter, which enclosesV a hollowspace above the screw conveyor, is closed in its axial direction andpossesses at least one entrance hole for compressed air leading, intothis hollow space at right angles to the tube axis', and also an escapehole opposite said entrance hole.

The attached drawing illustrates one embodiment of the invention. Itshows:

Fig. 1 a longitudinal section of the arrangement,

Fig. 2v a top view ofthe same,

Fig. 3 a section ofthe conveyor-tube and screw conveyor' along line I-Iin Fig. 1,

Fig. 4 a section along line II-II inV Fig. l,

Fig. 5 likewise a section of Vthe screw conveyor along line III-III inFig. 9,

Fig. 6 the sand diffusion vane,

Fig. '7 a View of the screw conveyor with sand diffusion vane,

Fig. 8 a top view of Fig. '7,

Fig. 9 a section along line IV--IV in Fig. '7.

Material-container I is fixed to hollow shaft 2 which is mounted inbearing 3. On the lower end of hollow shaft 2 is fitted driving-wheel d,e. g. a spur-gear, which serves to drive container I. Inside hollowshaft Z is placed hollow spindle 5 driven by toothed Wheel 6'. Screwconveyor I is interchangeably inserted in hollow spindle 5 and tightlyfastened with a key. The upper edge of containerV I is covered by ringil with angular cross-section. This ring 8 is attached to struts 9 of astand which is not shown. On ring is fastened cross-piece I@ which iswelded to conveyor tube I I. Conveyor tube I l dips right down to thefloor of container I, though it does not actually touch it. The upperend of the conveyor tube is closed by means of plate I2, lying at rightangles to its axis. Between this plate and the upper end of screwconveyor 'I is hollow space I3 into which lead injection openings III,arranged in a semi-circle, for the purpose of introducing the compressedair, which is supplied through pipe I5. Opposite injection openings I lis exit It, through which the compressed air blows the material Via pipeIl to the spray pistol. rIhrough entrance-hole 2li provided in the sideof conveyor tube I I the material which turns with container Ipenetrates into conveyor tube I I and is raised by screw conveyor l. Inorder to direct the material which turns with container I round conveyortube I I up into the latter, conveyor tube i l is equipped withdiffusion vane 2|. The screw conveyor can turn at the same speed ascontainer I in which case, it can be'rigidly connected with container I.It is, however, necessary, according to the kind of material to beconveyed, that the screw conveyor should turn at a higher speed than, oreven in the opposite direction to, container l. For this reason it is'of advantage to give both screw conveyor 'I'and container I their ownseparate drive, which is best fitted With a device for regulating thenumber of revolutions.

Figs. 5, 6, '7, 8 and 9 show in particular the material-regulatingarrangement by means of which the material is transferred from thecontainer to theconveyor tube.

Fig. 5 shows conveyor tube II, which is coated on the inside with rubberlining 22, as it has been found that rubber resists .sand abrasionbetter than metal. In addition, particles of sand which have becomejammed may be pressed into the rubber and in this way escape the screwconveyor. The difference between the outer diameter of screw conveyor 'Iand' the inner' diameter of the rubber lining of the conveyor` tube istwice as large as the largest particle of sand to be conveyed. Thepurpose of this is:

1. To prevent any particles of sand from getting jammed between theinner casing of the conveyor tube and the screw conveyor, and

2. To cause a layer of material to settle on the casing, so that thefriction of the material conveyed does not operate directly on thesurface of the conveyor tube lining.

The air-pressure required for blowing out and spraying the material isabout 6 atmospheres. At this pressure there is a danger that thecompressed air may force its way through the conveyor tube between thethread of the screwl conveyor and escape through the sand in thecontainer. In order to prevent this, it is necessary that an air-tightplug be formed in the conveyor tube by the material itself. This isachieved by the material being pressed together by the screw, so as toform a plug which is impervious to the compressed air.

It is, therefore, of advantage for screw conveyor and conveyor tube tobe designed in such a manner that the feed aperture for the material inthe conveyor tube is at least of the same width as one thread of thescrew, and that above the feed aperture at least one such thread is leftto press the sand upwards, in order to form a suciently airtight plug.For the purpose of directing the material turning with container lthrough aperture 29 of the conveyor tube to within reach of the screwconveyor, diffusion vane 23 is best arranged in front of the aperture;diffusion vane 23 can rotate round axle 2d and lie adjusted at an angleto the tangent of the conveyor tube. To this end, 4axle 24 of diffusionvane 23 is equipped with lever 25 which can be clamped in variouspositions by means of a winged screw. A greater or lesser quantity ofmaterial is conveyed into the screw conveyor according to the angularadjustment ,of this diffusion vane. As the material to be conveyedusually consists of a mixture of sand and cement or sand and lime, ittends to form lumps. The supply of material to the conveyor tube mustcorrespond, therefore, as closely as possible to the conveying capacityof the screw. In order to prevent the material from banking up in frontof the diffusion vane it is of advantage to equip the conveyor tube infront of the feed aperture with a projection 2l' about 1 cm. in lengthwhich defiects the material, so that a space is formed between thisprojection 2l and diffusion vane 23 in which no lumps can develop,whereby the material passes on regularly to the screw conveyor.

The operation of the apparatus is as follows:

The container is filled with sand or a sand mixture, which flows, forexample, from a mixing drum, and is set in motion over wheel 4 at thespeed of 30 revolutions per minute by means of a drive, not shown here.At this speed the centrifugal force is not strong enough for the mixtureto separate. Passing round the conveyor tube and past the appurtenantdiffusion vane, the material is conveyed within reach of the screwconveyor, which turns either at the same speed as container I or faster.This screw conveyor presses the material in the conveyor tube upwardsand forms in the latter a stop plug which prevents the compressed airfrom escaping through the conveyor tube. Compressed air enters thehollow space at the upper end of the regular quantity of material.

conveyor tube through nozzles I4 and drives out the material conveyed bythe screw.

The quantity of material conveyed depends on the number of revolutionsof the screw conveyor and can be adjusted exactly to the requiredproportions by regulating this number of revolutions. It remainsconstant because at a certain number of revolutions the screw conveyorconveys a This makes it possible to feed to the ow of material which isdriven oif a determined amount of liquid, so that the consistency of thepaste sprayed remains unvaried.

I claim:

1. Apparatus for drawing sand and sand mixtures from a container,comprising a container having a charging opening for filling the samefrom above, a conveyor tube disposed within the container and extendingto approximately the bottom of the container, the tube having an inletfor the sand adjacent the bottom thereof, means for rotating thecontainer relatively to said tube, a screw conveyor rotatable within thetube for raising the sand or sand mixture therein, means for driving theconveyor, said tube enclosing a hollow space above the screw conveyorand being closed in the axial direction, said tube having at least oneinjection opening for compressed air leading into the said hollow spaceand arranged transversely to the conveyor-tube axis, and provided with adischarge opening opposite the first opening forthe mixture of sand andconveying air.

2. Apparatus according to claim 1 wherein the conveyor and container arecoaxially disposed and wherein the driving means for rotating thecontainer and screw conveyor operate simultaneously.

3. Apparatus according to claim 1 in which the inlet in the conveyortube is constituted of an opening in the side of the tube.

4. Apparatus according to claim 1 in which the inlet in the conveyortube is constituted of an opening in the side of the tube, and adiffusion vane supported adjacent to such inlet for deecting materialthereinto.

5. Apparatus according to claim 1,. in which the inlet in the conveyortube is constituted of an opening in the side of the tube, and adiffusion vane supported adjacent to such opening for directing materialthereinto, said vane being adjustable to extend at a sharp angle to thetangent of the conveyor tube.

6. Apparatus according to claim 1, in which the difference between theouter diameter of the screw conveyor and the inner diameter of theconveyor tube is equal to at least twice the size of the largestparticle of sand to be conveyed.

7. Apparatus according to claim 1 in which the inlet in the conveyortube is at least as wide as a thread fillet of the screw conveyor.

8. Apparatus according to the claim 1 in which the length of theconveyor tube above the inlet is at least equal to a thread of the screwconveyor.

9. Apparatus according to claim 1 in which the inlet in the conveyortube is constituted of an opening in the side of the tube and includinga vane supported adjacent to said inlet to de- Iiect material thereinto,and a defiector plate extending outwardly from the tube and in advanceof the vane to discourage the formation of lumps at the inlet.

10. Apparatus according to claim 1, in which the conveyor tube isprovided with a plurality of 5 6 charging openings for compressed air atthe UNITED STATES PATENTS discharge end thereof, said openings being ar-Num-Del. Name Date ranged approximately i a Sem'cm1e- 192,285 Rohrbacheret a1. June 19, 1877 HENRY TTSCH 837,113 Phillips NOV. 27, 1906 0859,863 Young et a1. July 9, 1907 1,013,379 Dunn Jan. 2, 1912 REFERENCESCITED lrtwood Apr. 2g, i321 K The following references are of record inthe 166682 .116111112371 Z lg me 0f this 'patenti l 1,966,325 Welch July1o, 1934

